Hinge Area Research Articles

Seismic Performance of the Bridge Piers Reinforced with PP-ECC in the Plastic Hinge Region

Ductility deficiency in reinforced concrete (RC) piers is a substantial factor contributing to earthquake damage in bridge structures. In this study, the conventional concrete in the potential plastic hinge area was substituted with polypropylene fiber-reinforced engineered cementitious composite (PP-ECC), thereby leveraging its high ductility characteristics to explore the seismic performance of RC piers strengthened by PP-ECC. A finite element model was established to discuss the reinforced height, axial compression ratio, longitudinal reinforcement ratio and stirrup ratio on the hysteresis performance by referring to a published paper with a 1/5 scale test specimen. Based on the results of the parameter analysis, an ideal set of configuration parameters was proposed. Subsequently, a full-size simplified mechanical model was established with ideal reinforcement parameters. Time-history and pushover analysis were utilized to test the seismic response. The study indicates that the two analytical methods were largely consistent. The improvement in the displacement and shear force of the strengthened pier gradually decreased with the increase in acceleration amplitude. Time-history analysis reveals a decrease in the enhancement of displacement from 82.26% to 17.98% and a reduction at the bottom reaction from 12.2% to 1.5%. Under the pushover analysis method, the retrofitting level of the top displacement decreased from 77.22% to 11.53%, whereas the improvement level of the bottom shear decreased from 9.62% to 3.69%. These results provide a theoretical basis and reference standard for the application of PP-ECC.

Yunfuconcha new genus, a possible stem-archiheterodont bivalve from the Ordovician of Guangdong, South China

ABSTRACT Yunfuconcha bimenta, a new genus and species of bivalve from the Ordovician of western Guangdong, China, is described. Its unusual hinge consists of a palaeotaxodont-like dentition anteriorly and a heteroconch-like dentition posteriorly. The posterior hinge area exhibits a remarkable, broad, deeply inset, concave ligament area, which is reminiscent of the ventrally expanded ligament of some Recent and fossil lucinoids and the triangular resilifer in late Palaeozoic crassatellid heteroconchs. Lamellar posterior teeth and sockets complete the posterior dentition. The unusual combination of features, normally associated with either the Order Cardiolariatida (used here in place of Order ‘Afghanodesmatida’—the type genus Afghanodesma, is known only from wax impressions rendering it and its nominal higher taxa invalid) or various crassatelloids and lucinoids, make systematic placement of Yunfuconcha n. gen. uncertain below subclass rank. In view of presumed derived heteroconch-like characters of the posterior hinge, we place Yunfuconcha n. gen. in the Subclass Autobranchia, possibly as a stem archiheterodont or a stem heteroconch.

PARAMETRIC ANALYSIS OF CFRP STRIPS INTERNALLY CONFINED RC COLUMNS

Fiber-reinforced polymer (FRP) sheets has been widely used as external confinement for retrofitting and strengthening structural elements as they increase axial, shear, and bending capacity. Despite many advantages, FRPs suffer from some drawbacks such as have weak durability against thermal and harsh environment. Thus, the use of FRP strips as internal confinement was proposed so that the concrete cover can protect the FRP strips. In this study, a three-dimensional (3D) nonlinear finite element (FE) model is developed using ABAQUS software to study the cyclic behavior of carbon fiber-reinforced polymer (CFRP) strips internally confined reinforced concrete (RC) columns. A validated model was used to conduct the parametric study to investigate the effect of FE model under different intensities of axial load (i.e. 70kN, 100kN, 200kN, 300kN, and 400kN) and distances between the CFRP spirals (100mm, 150mm, 200mm, and 250mm). Results indicate that an increase in the axial force has significantly increased the stress on the surface of concrete and can lead to the rupture of CFRP strips in the column. Meanwhile, increasing the distance between CFRP strips has increased the stress at the plastic hinge area and experienced buckling of longitudinal reinforcements at 250 mm of CFRP strips.

Can mechanical heart valves perform similarly to tissue valves? An in vitro study

Current surgical aortic valve (AV) replacement options include bioprosthetic and mechanical heart valves (MHVs), each with inherent limitations. Bioprosthetic valves offer superior hemodynamics but suffer from durability issues, typically initiating deterioration within 7–8 years. MHVs, while durable, necessitate lifelong anticoagulation therapy, presenting risks such as severe bleeding and thromboembolic events. The need for anticoagulants is caused by non-physiological flow through the hinge area during the closed phase and large spikes of regional backflow velocity (RBV) during the closing phase that produces high shear events. This study introduces the iValve, a novel MHV designed to combine the hemodynamic benefits of bioprosthetic valves with the durability of MHVs without requiring anticoagulation. The iValve features eye-like leaflets, a saddle-shaped housing, and an optimized hinge design to enhance blood flow and minimize thrombotic risk. Fabricated using 6061-T6 aluminum and polyether ether ketone (PEEK), twelve iValve iterations were evaluated for their opening and closing dynamics. The reported top-performing prototypes demonstrated competitive performance against industry standards. The proposed iValve prototype exhibited a mean RBV of −4.34 m/s with no spikes in RBV, performing similarly to bioprosthetic valves and significantly outperforming existing MHVs. The iValve’s optimized design showed a 7–10% reduction in closing time and a substantial decrease in RBV spikes, potentially reducing the need for anticoagulation therapy. This study highlights the iValve’s potential to revolutionize prosthetic heart valve technology by offering a durable, hemodynamically superior solution that mitigates the drawbacks of current MHVs.

Setting hinge position distal to the proximal margin of the distal lateral femur reduces the maximum principal strains of the hinge area and risk of hinge fractures.

The optimal hinge position to prevent hinge fractures in medial closing wedge distal femoral osteotomy (MCWDFO) based on the biomechanical background has not yet been well examined. This study aimed to examine the appropriate hinge position in MCWDFO using finite element (FE) analysis to prevent hinge fractures. Computer-aided design (CAD) models were created using composite replicate femurs. FE models of the MCWDFO with a 5° wedge were created with three different hinge positions: (A) 5 mm proximal to the proximal margin of the lateral epicondylar region, (B) proximal margin level and (C) 5 mm distal to the proximal margin level. The maximum and minimum principal strains in the cortical bone were calculated for each model. To validate the FE analysis, biomechanical tests were performed using composite replicate femurs with the same hinge position models as those in the FE analysis. In the FE analysis, the maximum principal strains were in the order of Models A > B > C. The highest value of maximum principal strain was observed in the area proximal to the hinge. In the biomechanical test, hinge fractures occurred in the area proximal to the hinge in Models A and B, whereas the gap closed completely without hinge fractures in Model C. Fractures occurred in an area similar to where the highest maximal principal strain was observed in the FE analysis. Distal to the proximal margin of the lateral epicondylar region is an appropriate hinge position in MCWDFO to prevent hinge fractures. Level V.

Experimental Study on Mechanical Coupler Splices in Reinforced Concrete Beams under Cyclic Flexural Loading

This study presents an experiment on the utilization of rebar waste as a mechanical coupler splice material on the reinforced concrete beam. The purpose of using rebar waste is to save costs in a construction project. Experiments were conducted with 3 test specimens, which are reinforced concrete beam without coupler splice (B-13NC), reinforced concrete beam with 19 mm diameter coupler splice (B-13C19) and reinforced concrete beam with 22 mm coupler splice with welding (B-13C22W). Each coupler splice was installed in the plastic hinge area of the beam to determine the maximum capability of the coupler splice. Tests were conducted under cyclic flexural loading on the reinforced concrete beam. The results showed that the 22 mm diameter coupler splice at B-13C22W has almost the same strength as the reinforced concrete beam without coupler splice (B-13NC). However, the 19 mm diameter coupler splice has a significant decrease in strength, which is more than 30% of the strength of the reinforced concrete beam without a coupler splice (B-13NC). This experiment also shows that the utilization of a coupler splice in the reinforced concrete beams results in a decrease in structural ductility.

Study on Seismic Mechanical Properties of Reinforced Concrete Energy Dissipation Wall and Seismic Response Analysis of Structure

Utilizing the nonlinear finite element analysis software, ABAQUS, an examination is undertaken to evaluate the ductility characteristics and seismic design methodologies pertinent to a representative reinforced concrete hollow high pier. The research encompasses several focal areas: elucidation of seismic design strategies related to ductility categories, exploration of plastic energy dissipation mechanisms, determination of ductility indices, and delineation of structural measures to enhance ductility. Employing the nonlinear FEA software, ABAQUS, it is recommended that the longitudinal reinforcement ratio for ductile piers fall within the range of 0.6% to 4%. Furthermore, for flexible bridge piers, the maximum spacing of confinement reinforcements should either exceed 100 mm, be sixfold the diameter of the longitudinal reinforcement, or equate to at least one-quarter of the pier column’s bending direction section width. Combined with the influence of high pier ductility seismic axial pressure ratio, reinforcement, concrete factors such as factor analysis results, put forward and checking a reinforced concrete hollow high pier ductility seismic optimization scheme, increase the strength of the plastic hinge area section, through the comparative analysis in different seismic strength of plastic hinge unit cloth, maximum ductility coefficient and pier top displacement to verify its influence on the ductile seismic.

Finite Element Analysis of Protective Measures against Lateral Hinge Fractures in High-Tibial Osteotomy.

Opening wedge high-tibial osteotomy (OWHTO) is widely used for correcting mechanical axis deviations and offloading the medial compartment in unicompartmental osteoarthritis. However, lateral hinge fractures (LHFs) pose a significant complication. This study investigates protective measures to mitigate these fractures, guided by prior observations of mechanical stress impact on LHFs. The study aims to assess the effectiveness of different protective measures, specifically the use of varying sizes of Kirchner wires and drill holes, in reducing the incidence of LHFs during OWHTO. Study Design. The study employs a quantitative, comparative analysis using a finite element method (FEM) based on computed tomography (CT) scans. Using CT-based FEM, the study compares the impact of different sizes of K-wires (1.6 mm, 2.0 mm, and 2.5 mm) and drill holes (3.2 mm and 4.5 mm) on the mechanical stresses around the hinge area in OWHTO. The models were created from a CT scan of a healthy 33-year-old male, focusing on the force required to open the osteotomy gap and the incidence of cracked shell elements. The study found that thicker K-wires increased the force required to open the osteotomy gap, whereas larger apical holes decreased it. The 4.5 mm apical hole model demonstrated significantly fewer cracks compared to the 2.0 mm K-wire model, with no significant difference observed compared to the 2.5 mm K-wire model. Models using a 1.6 mm K-wire or a 3.2 mm drill hole did not significantly reduce cracks compared to the base model. The findings suggest that a 4.5 mm drill hole may be more effective in reducing the risk of LHFs compared to thinner diameter K-wires or smaller apical holes. Both a 2.5 mm K-wire and a 4.5 mm drill hole reduce the number of cracked elements, but the 4.5 mm drill hole also significantly decreases the average and maximum principal stresses as well as the average tensile strength ratio at the hinge area. These findings may be important for surgical planning, particularly in cases requiring increased osteotomy distraction.

Using a patient-specific cutting guide enables identical knee osteotomies: An evaluation of accuracy on sawbones

PurposeIt was hypothesized that using a Patient-Specific Cutting Guide (PSCG) would allow the creation of sawbones model osteotomies, identical in the 3 planes and the hinge parameters, that can be used for biomechanical studies. The aim of the study was to evaluate the accuracy of the PSCG system and to introduce and assess the new hinge parameter; the hinge area. MethodsSix identical sawbones tibia models were identically set up for identical osteotomy cuts by the same surgeon in the same session and with identical instruments. A medical scanner was used to evaluate the 3D configuration of all the specimens. The analyzed parameters included the cutting angles in both the coronal and sagittal planes (degrees) and the hinge and the slicing areas (cm2), and the hinge thickness (mm). The values were statistically evaluated for average, standard deviation, 95% confidence index, and delta to the expected values were calculated. ResultsThe mean values for the coronal and sagittal angles were 110.5̊±1̊ and 89.8̊±0.8̊, respectively. The 95% confidence index level ranged between 0.1̊, and 0.8̊ in both the coronal & the sagittal planes. The mean values for the hinge thickness, the hinge area, and the slicing area were 12.7±1.5mm, 4.2±0.9 cm2, and 18.3±1.2 cm2, respectively. ConclusionIn the presented study, it can be demonstrated that mechanically identical osteotomy specimens, with regard to the cutting planes and hinge parameters, can be reliably created using the PSCG. The identical specimens can be used for biomechanical research purposes to further expand our knowledge of the factors affecting osteotomy outcomes. Level of evidenceIV.

Impact of support instruments in medial closed-wedge distal femoral osteotomy: a finite element analysis.

Medial closed-wedge distal femoral osteotomy (MCWDFO) is a valuable treatment approach for lateral knee osteoarthritis with femoral valgus deformity. Improved results have been reported with the upgrade of surgical techniques and locking plates. However, the risk of nonunion and loss of correction increases in cases of lateral hinge fractures. This study aimed to evaluate the mechanical impact of hinge fractures and support instruments in MCWDFO using finite element analysis (FEA). Five femur models were developed using Mechanical Finder 11.0 FEA software. We simulated the following models: only a medial locking plate (MLP) (group A); an MLP with a lateral support screw (group B); and an MLP with a lateral support plate (group C). The equivalent stress around the hinge was evaluated and the percentage of the plastic deformation zone was calculated for the hinge area in the no-hinge fracture model. The equivalent stress of the MLP and the degree of displacement were calculated using the hinge fracture model. The percentages of the plastic deformation zone in groups A, B, and C were 18.0 ± 11.7%, 3.3 ± 2.4%, and 2.3 ± 2.8%, respectively. The percentages tended to be lower in groups B and C than in group A. In the hinge fracture model, the mean equivalent stress of the MLP in group C was significantly less than that in group A. In terms of the mean degree of displacement, group A showed more than 1mm of displacement, which was significantly larger than that of the other groups. The support instruments provided stability to the hinge site and reduced the equivalent stress of the main plate in the MCWDFO with hinge fractures. No significant difference was observed between the two instruments in terms of stability.

Evaluation of pliable bioresorbable, elastomeric aortic valve prostheses in sheep during 12 months post implantation

Pliable microfibrous, bioresorbable elastomeric heart valve prostheses are investigated in search of sustainable heart valve replacement. These cell-free implants recruit cells and trigger tissue formation on the valves in situ. Our aim is to investigate the behaviour of these heart valve prostheses when exposed to the high-pressure circulation. We conducted a 12-month follow-up study in sheep to evaluate the in vivo functionality and neo-tissue formation of these valves in the aortic position. All valves remained free from endocarditis, thrombotic complications and macroscopic calcifications. Cell colonisation in the leaflets was mainly restricted to the hinge area, while resorption of synthetic fibers was limited. Most valves were pliable and structurally intact (10/15), however, other valves (5/15) showed cusp thickening, retraction or holes in the leaflets. Further research is needed to assess whether in-situ heart valve tissue engineering in the aortic position is possible or whether non-resorbable synthetic pliable prostheses are preferred.

The improvement of the threaded-based mechanical splice by modifying the threaded system: Study of techniques cold rolling and rotating friction welding

In this study, by modifying the method of making a threaded splice and combining it with rotary friction welding, two types of patches are introduced. The aim is to modify the failure area of the coupler with a threaded bar and use it in the plastic hinge areas of ductile members in seismic areas. The splice area in the suggested method is oversized. To enlarge the splice area, two techniques-cold rolling and rotating friction welding are used. In total, 96 samples (including three repeated samples of each type) were tested. Threaded couplers (TC), oversize-threaded couplers (OTC), rotary friction welding splices with threaded couplers (RFWTC), and non-spliced reference specimens underwent uniaxial tensile and cyclic testing with and without concrete (NS). The sensitivity to bar diameter, as well as bar strength, ductility, energy absorption, and failure mode performance, were evaluated. In terms of strength, ductility, energy absorption, and failure mode, the RFWTC and OTC performed the best and are suited for usage in high seismic zones. Additionally, the TC is appropriate for use in low-to-medium seismic zones. Also, the predicted model is sufficient to estimate the ultimate tensile strength of the threaded couplers.

Experimental Study of Precast Beam Joints Using Steel Plates in Beam-Column Joints Due to Cyclic Loading

In seismic design, reinforced concrete structures must perform well under heavy load conditions. To withstand large lateral loads without severe damage, structures require strength and energy dissipation capacity. It is generally not economical to design reinforced concrete structures to the greatest possible ground motions without damage. Therefore, the need for ductility must be weighed against economic constraints. This research is focused on dry joints where the joints are on beams in the plastic hinge area and modeled using steel plates, this modeling will be compared with the hysteresis and ductility curves in three types of specimens namely BU-1 without using plate joints, BU-2 using plate joints measuring 300mm x 400mm, BU-3 plate joints measuring 200mm x 400mm, with the same thickness and quality, namely 8mm thick and Fu 370 MPa. To strengthen the use of the plate connection, A325 bolts with a diameter of 12 mm and Fu 620 MPa are used. The results show that the pinching effect is found in the hysteresis curve of the BU-2 and BU-3 specimens. Meanwhile, for the ductility test at peak load, namely the seventh ductility for BU-1, the value is still better than BU-2 and BU-3. These results can still be improved with several variations of plate thickness, for this reason, further studies are recommended to develop and increase recommendations for several variations of plate joints, because precast joints, especially dry joints, are still the focus of research, especially in Indonesia.

Seismic Analysis of Reinforced Concrete Bridge Piers Based on Ductile Reinforcement

The reinforced concrete (RC) piers were often damaged at the plastic hinge area by earthquake, therefore, it is necessary to strength the plastic area to resist seismic load. In this study, four RC piers were cast whose dimension was 1/10-scale to the practical one and the main reinforcement ratio was consistent with the practical one. Three of specimens were strengthened by three different materials, such as glass fiber-reinforced polymer (GFRP), aramid fiber-reinforced polymer (AFRP), and hoop stirrup, which were easier to acquire and cost friendly compared with other strengthening methods. These four piers were loaded by a quasi-static test and finite element analysis (FEA) were also conducted. From the experimental results, specimen strengthened by AFRP had best performance, which the lateral resistance, ductility, and energy dissipation of specimens were 16.33%, 34.32%, and 60.58%. GFRP strengthening pier, however, had poor performance in lateral resistance increase of 8.09%, ductility and energy dissipation capacity which the increases were 19.44% and 22%, respectively. The results of FEA are consistent with the experimental results. AFRP had a best performance, which the lateral resistance, ductility, and energy dissipation of specimens were 8.07%, 32.32%, and 45.61%. Compared with the control one, seismic behavior of three strengthened piers had considerable improvement which can be referred to the practical strengthening piers.

Relationship between programming stress and residual strain in FDM 4D printing

4D printing with fused deposition modeling (FDM) enables the production of smart structures using smart materials that can change their shape over time. During the printing process, stresses are introduced into the structure that are relieved when exposed to an external stimulus, in this case, when raising the temperature above the glass-transition temperature TTrans\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{Trans}$$\\end{document}. This article investigates the relationship between stress and strain during 4D printing. We mounted the print platform on load cells to measure the forces in x-direction during printing. Flat hinges made of PLA are printed and are activated by immersion in hot water, which causes bending of the hinge areas. We varied nozzle temperature, print speed, and melt zone length to investigate their influence on programming force and post-activation curvature. Programming force and curvature translate into stress and strain, when specimen geometry is taken into account. The results are approximated by a linear relationship between programming stress and recovery strain. However, these gradients are different for each printing parameter. Lower nozzle temperature, shorter melt zone and higher print speed all result in higher forces and higher curvatures. However, increasing the forces by raising print speed results in a smaller increase in curvature than when the same increase in force is applied by lowering nozzle temperature. This is partly due to the heating and cooling process of the structure, which in turn depends on the printing parameters.

Optimal additional support screw position for prevention of hinge fracture in biplanar closed wedge distal femoral osteotomy

BackgroundThe purpose of this study was to examine the biomechanical significance of supplemental fixation using a positional screw in prevention of the hinge fracture in lateral closed-wedge distal femoral osteotomy (LCW-DFO) by means of a three-dimensional finite element analysis. MethodsThe three-dimensional numerical knee models with LCW-DFO were developed. To assess the mechanical efficacy of the positional screw and determine its optimal position and orientation, in total, 13 screwing methods were analyzed. In the first four methods, the screw was supported by the cortical bone only on the medial surface (mono-cortical). In the other 9 models, the screw was supported by both medial and lateral cortical bones (bi-cortical). Under 1000 N of vertical force and 5 Nm of rotational torques, the highest shear stress value around the medial hinge area was adopted as an analytical parameter. ResultsIn mono-cortical methods, with the cancellous bone support, all methods were able to reduce the highest stress value compared to the value without the screw, while the efficacy was rather inferior when the screw was in horizontal direction. Without the cancellous bone support, however, all methods were not able to reduce the stress value. In bi-cortical methods, with the cancellous bone support, almost all screw augmentation methods were able to reduce the stress value. When screwing from the medial to the lateral, it only gets worse when going extremely posterior. Without the cancellous bone support, all methods were able to reduce the stress value. ConclusionThe mechanical efficacy of the bi-cortical method was proven regardless of the quality of the local cancellous bone.

Seismic behavior and shear capacity of shear-dominated T-shaped RC walls under cyclic loading

T-shaped walls are widely applied in tall buildings because of their high stiffness and the demand for structural layout, but the flange affects the shear performance of the wall. To investigate the shear failure mechanism of shear-dominated T-shaped reinforced concrete (RC) walls and the difference between the shear performance in the flange-in-tension and flange-in-compression directions, cyclic tests were carried out on three T-shaped RC walls. Numerical models were established for the parametric analysis of shear capacity in different loading directions, and the shear capacity calculation in various specifications was evaluated. The results showed that the failure regions of both specimens with flexural and shear failure were concentrated at the web tip, and the web tips of the shear failure specimens were more seriously damaged. Furthermore, reducing the shear span ratio significantly reduced ductility and energy dissipation capacity and increased the proportion of shear deformation to the total deformation in the plastic hinge area. The decrease in the horizontal distribution reinforcement ratio resulted in the slitting of the T-shaped wall, and the increase in deformation capacity owing to the slit wall compensated for the reduction in deformation capacity caused by the enhancement of the shear effect. Based on the results of the numerical simulation, the current codes failed to consider and distinguish the effect of the tensile and compressive flanges on the shear capacity of the T-shaped wall and were unable to predict the shear capacity of the T-shaped wall well.

Ductility and Distribution of Strains on Column Reinforcement Retrofit with Wire Mesh

Abstract A lot of damage to building structures due to earthquakes is damage to column components that serve as vertical elements to pass the load to the foundation. Ductility is one of the parameters that must be owned by the column and as part of the column, longitudinal reinforcement is part of the column element that is quite vital and one of the parameters that can be studied is the distribution of strains that occur in longitudinal reinforcement when burdened with cyclic loads. In this study, a study of the ductility and distribution of strain values occurred in the reinforcement of control columns and retrofit columns with wire mesh size M6. From the test results in can be that on the column that is retrofit with wire mesh and SCC experienced an increase in the value of ductility. While the strain value on the reinforcement of the control column and retrofit column tends to enlarge when it is in the plastic hinge area of the column. In the control column the strain value that occurs in the plastic hinge area is greater than the strain value in the retrofit column, so that in the control column the plastic hinge mechanism has begun to form, while in the retrofit column the plastic hinge mechanism has not been formed due to higher stiffness.

Topology Optimization Design of Multi-Input-Multi-Output Compliant Mechanisms with Hinge-Free Characteristic and Totally Decoupled Kinematics

A new multi-constraint optimization model with the weighted objective function is proposed to design the multi-input-multi-output (MIMO) compliant mechanisms. The main feature of this work is that both the two notable problems related to the de facto hinge and the movement coupling are tackled simultaneously in the topological synthesis of MIMO compliant mechanisms. To be specific, the first problem is the severe stress concentration in the flexible hinge areas, and it is solved by the introduction of input and output compliances into the objective function, which could facilitate the optimization to strike a good balance between structural flexibility and stiffness. The second problem is the high degree of control complexity caused by the coupled outputs and inputs, and it is addressed by achieving the complete decoupling with two groups of extra constraints that are used to suppress the input coupling and the output coupling, respectively. As the most common and effective topology optimization method, the Solid Isotropic Material with Penalization (SIMP)-based density method is adopted here to obtain the optimized configurations. After the analytical sensitivity deduction related to the weighted objective function and constraints, two typical numerical examples are presented to demonstrate the validity of the proposed topology optimization framework in designing the hinge-free and completely decoupled MIMO compliant mechanisms.

Finite element analysis of the response of conventional and special reinforcement detailed concrete beams subjected to impact loads

This study numerically investigated performance of RC beams with conventional and special reinforcement detailing provisions prone to incremental drop weight impact loads using nonlinear explicit finite element modelling in LS-DYNA. In this study, the effect of strain rate on both concrete and reinforcing bars, material model formulations, was considered together with contingent reinforcement details in plastic hinge areas. The accuracy of the developed numerical model was validated by experimental data reported in literature. Parametric study was conducted on the effect of reinforcement steel ratio, concrete compressive strength and reinforcing steel yield stresses to get insight into impact load response of special reinforcement detailing concrete beam under incremental drop weight.Finite element analysis results showed an increase in specified compressive strength of concrete, reinforcing steel yield stresses, and reinforcement steel ratios resulted a drop in midspan displacement and a meaningful surge in internal energy of a system. Moreover, as compared to conventionally detailed RC beam, special detailed concrete beam around plastic hinge regions exhibited excellent performance against the impact load.